What affects dissolved oxygen?

What affects dissolved oxygen?

Temperature

Temperature is one of the biggest factors that directly affects dissolved oxygen. Temperature itself is a measurement of the energy of motion within a system. The higher the temperature, the lower the DO concentration. Inversely, as temperature decreases, particle motion decreases, and therefore DO concentrations go up.

Pressure

Pressure when talking about dissolved oxygen, refers to atmospheric pressure. Have you ever been at sea level and then traveled to a place of higher elevation such as Denver, CO? You may have noticed that you feel a bit lighter, but also that the air feels “thinner”. There is less atmospheric pressure pressing down at that altitude. When atmospheric pressure decreases, the partial pressure of oxygen decreases too. As altitude increases, the concentration of DO decreases since there is not as much pressure keeping the oxygen diffused into the liquid. As atmospheric pressure increases, the partial pressure of oxygen increases as well. So, as altitude decreases, the concentration of DO increases.

Salinity

Salinity can also affect the amount of DO in a solution.  As salinity increases, DO will decrease.

Humidity

Humidity or water vapor can affect DO concentration, and the calibration of certain DO measurement technologies. When you have an increased humidity level, you have an increased partial pressure of oxygen, and therefore you have an increased level of dissolved oxygen.